Lifting jack



May 18, 1937. A. R. BRUSH 2,080,530

Y LIFTING JACK Filed May 27, 1936 2 Sheets-Sheet l Effi/7m!" E. Eras/7 n ll A. R. BRUSH May 18, 1937.

LIFTING JACK Filed May 27, 195e 2 sheets-sheet 2 QM n tot Eri/5m j?. EPL/5]:

Patented May 18, 1937 UNlTED STATES PATENT GFFICE LIFTING JACK Application May 27, 1936, Serial No. 82,135

6 Claims.

'Ihis invention relates generally to improvements in lifting jacks, and more particularly to jacks of that type in which the base and lifting members are extensible in opposite directions with respect to a central operating screw-threaded rod.

The main object of the invention is to provide a quick acting lifting jack of great power, which can be very easily operated, and which can be manufactured in quantities and very cheaply from standard sizes of cold drawn steel tubing.

A further object of the invention is to provide a jack of this character which because of its peculiar construction, can be made very small l5 and of light weight in comparison with other jacks of the same power.

Other objects of the invention will become apparent as the detailed description thereof proceeds.

2O In the drawings: Y

Figure 1 is a central vertical section through the jack forming the subject matter of this application;

Figure 2 is a fragmentary end elevation of part of the jack operating mechanism;

Figure 3 is a horizontal section taken on the line 3 3 of Figure 1;

Figure 4 is a horizontal section taken on the line 4--4 of Figure 1;

Figure 5 is a fragmentary central vertical section of parts of the jack shown in Figure 1, but with the parts in a different position; and 5 Figure 6 is a fragmentary detail, partly in sec-v tion, illustrating means for operating a pawl which forms a part of the jack.

As shown in the drawings, the invention comprises a base plate 'l having an internally screwthreaded tube 8 extending upwardly from the center thereof. A rod 9 having a cylindrical central body portion is provided with right and left screw-threaded portions I0 and II. The screwthreads on the lower portion I0 engage correspondingly inclined threads on the tube 8; while the screw-threads on the portion II engage the correspondingly inclined screw-threads on an upper tube I2.

A sleeve I3 is mounted to slide snugly on the outer cylindrical surface of the tube 8; and is prevented from rotation about the axis of the tube 8 by means of a stud I4 projecting from the lower end of the sleeve I3 into a groove I5 formed lengthwise in the outer surface of the tube 8. An upper sleeve I6 is slidably mounted on the outer cylindrical surface of the upper tube I2; and is rigidly connected to the lower sleeve I3 by yokes II and I8 which are welded or otherwise suitably secured to the upper end of sleeve I3 and the lower end of the sleeve I6 to hold the aforesaid ends spaced apart a sufficient distance to accommodate the furcations I9 and 2) of a bifurcated operat- 5 ing lever 2l.

The furcations I9 and 2G are provided with registering apertures 22 and 23 which receive the central cylindrical portion of the operating rod 9. Between the furcations I9 and 20 there is also 10 suitably secured to the cylindrical portion of the rod 9, a spur gear 34. The slot formed between the furcations I3 and 2Q extends suiciently beyond the outer periphery of the gear 24 to receive a double acting pawl 25, which is fixed to a pivot 15 rod 26 extending through the furcations I9 and 20 of the lever 2l A handle 21 xed to the upper end of the pivot rod 23 is adapted to move the pawl 25 in either direction to determine the direction of rotation of the gear 24 and the operating 20 rod 9 to which it is xed.

A spring l28 (see Figures l and 3) has one end y secured to the furcation 20, and has its other end secured to the handle 2l at a point intermediate the axis of pivot 23 and the outer end of the handle. This is a snap-over spring of well-known type, designed to hold the handle 2l and the pawl mechanism connected thereto, in proper position to determine the rotation of the gear 24 when the lever 2| is oscillated about the axis of the operating screw.

The upper sleeve I6 is provided at its upper end with a stud 29 slidably seated in a groove 30 formed in the upper screw-threaded tube I2 to prevent relative rotation of the tubes 8 and I2. It will be apparent from the drawings that when the lever 2l is oscillated and the pawl 25 is properly positioned, this oscillation will cause the right and left hand screw-threads of rod 9 to rotate about the axis of said rod. This rotationV causes the rod 9 to rise bodily in the tube 8, which acts as a nut for the lower screw-threaded portion of the rod 9. In so rising, the rod 9 carries with it the sleeves I3 and I 6, since both sleeves are rigidly connected to each other by the yokes II and 45 I8. At the same time, the tube I2 is caused to rise on the upper screw-threaded part II of the operating rod 9, since it is held against rotation by the engagement of the stud 29 with the groove 33. The gear 2d during this oscillation of the 50 lever 2 I, is yieldingly held against rotation by the drag of the pawl by means of a ball 3| seated in a bore 32 formed in the yoke I8 and against the spring 33 positioned in said bore by a machine SCTBW 34. 55

Y heavy loads.

The tube I2 at its upper end is recessed to provide a seat for a nut 35, which may be welded or otherwise secured in its seat, engaging screwthreads 36 on a liftingl rod 31 manually adjustable relative to the tube l2. The operating rod 9 is bored axially to receive the rod 31 slidably. A cap 38 is xed to the outer end of the rod 31. The parts are so proportioned that when the rod 31 is screwed out to its limit, part thereof Will always remain in the bore of the rod 9 to prevent buckling of the jack when fully extended under In effect, the nut forms an inwardly directed screw-threaded iiange at the upper end of the tube l2 to support the manually adjustable rod 31.

As appears in Figures i, 3, and 4 of the drawings, the lever 2| is provided with a comparatively short handle 39 which may be operated to rotate the gear 24 whenever the object to be lifted is located to permit such operation. However, where the jack must be positioned in some location where it is not convenient to operate the handle 39. directly, there is provided an extension 40 having a socket 4| at one end thereof to fit snugly over the handle 39. The socket 4I and the handle 39 are provided with registering apertures to receive a pin 42 which may be held in convenient position on the extension member 40 by a chain or other flexible member 43.

It will be apparent from the drawings and as previously described, the handle 21 may be moved in one direction or the other to position the pawl 25 for engagement in either direction with the teeth of the gear 24. In order to position this paWl when the extension 40 is used, there is se- Vcured to the said extension 40 a tube 44 through which extends slidably, a wire 45 having an operating knob 46 secured to the outer end thereof. The inner end of the wire 45 is bent to engage a bore 41 formed near the outer end of one arm of the pavvl 45. By this means, the pawl 25 may beroperated in either direction, even when the jacl; is so positioned that the hands of the operator cannot reach the handle 21. The spring 28 holds the wire 45 in whatever position it may have been moved in locating the pawl 25 against the teeth of gear 24.

It is to be understood that the invention is not to Ybe consideredv as limited to the specic construction and arrangement described herein, since from the center thereof, one of said'parts having.

its threads engaging the threads in said tube, a secondtube internally screw-threaded to receive thev screw-threads on the other part, a sleeve slidable on Vthe first named tube, said tube having a groove extending lengthwise of its outer surface,

l a stud projecting from the lower end of'said sleeve into said groove, a sleeve slidable on said second tube, said second tube being provided with a groove extending lengthwise of the outer surface, a stud projecting from the upper endy of the second sleeve into the groove on the second tube. means for rigidly connecting said sleeves to each other, said operating rod being boredA axially, a lifting rod adjustable on the upper end of s aid secondl tube and having part thereof slidable inthe bore of said operating rod.

2. A jack comprising a base, an internally screw-threaded tube fixed to said base, an operating rod having left and right externally screwthreaded parts extending in opposite directions from the center thereof, one of said parts having its threads engaging the threads in said tube, a second tube having internal screw-threads engaging the screw-threads on the other of said parts, means for rotating said operating rod about its axis, a sleeve slidable on the rstnamed tube, a second sleeve slidable on the second named tube, means for rigidly connecting said sleeves to each other, cooperating means on said sleeves and tubes to prevent rotation of said operating rod, said operating rod being bored axially, said second tube having a screw-threaded flange extending over the upper end of said operating rod, and a lifting rod slidable in the bore of said operating rod, and having a part thereof in screw-threaded connection with said flange.

3. A jack comprising a base, an internally screw-threaded tube fixed to, said base, an operating rod having left and right externally screw-threaded parts extending in opposite directions from the center thereof, one of said Vparts having its threads engaging the threads in screw-threaded tube fixed to said base, an operating rod having left and right externally screw-threaded parts extending in opposite directions from the center thereof, one of said parts having its threads engaging the threads in v said tube, a second tube having internal screwthreads engaging the screw-threads on the other of said parts, means for rotating said operating rod about, its axis, asleeve slidable on the second named tube, a second sleeve slidable on the scond named tube, means for rigidly connecting said sleeves to each other, cooperating means onsaid sleevesv and tubes to prevent rotationof the second tube about its axis during the rotationV of said operating rod, said operating rod being axially bored, anda lifting rod slidable in the bore of said operating rod and adjustably con,-` nected to the second named tube.

5. A jack comprising a base, an internally screw-.threaded tube fixed to said base, an operating rod having left and right externally screwthreaded parts extending in opposite directions from the center thereof, one of said parts having its threads engaging the threads insaid tube, a secondtube internally screw-threadedto receive the screw-threads on the other part, a Sleeve, slidable on the first named tube, said tube having a groove extending lengthwise of its outersurface, a stud projecting from thelower end of said sleeve into said groove, a. `sleeve slidable on said second tube, saidV second tube being provided with a groove extending lengthwise of its outer surface, a stud projecting from the upper end of the second sleeve intoy the grooveon the. second tube, means for rigidly connecting saidsleeves to each other, said operating rod being axially bored, and a lifting rodl slidable inthe bore of said operating rod and adjustably connected to the second named tube.

6. A jack comprising a base, an internally screw-threaded tube fixed to said base, an operating rod having left and right externally screwthreaded parts extending in opposite directions from the center thereof, one of said parts having .its threads engaging the threads in said tube, a

second tube internally screw-threaded to receive the screw-threads on the other part, a gear fixed to the center of said operating rod, a handle 

